This application claims priority to Japanese Application Serial No. 2001-25889, filed Feb. 1, 2001.
The present invention relates to a biopolymer detector capable of detecting presence/absence of biopolymers such as DNA, RNA, protein or the like in a sample, and measuring a present amount or a concentration thereof.
A typical method of a conventional DNA detection technology has been to modify DNA with a radioactive material, fluorescent dye or the like by using a radioactive isotope (RI), fluorescence technology or the like, excite the DNA by an external stimulus, and then observe its response based on light emission. A charge detection method has also been invented, which makes electrochemical determination by using intercalating agents specifically coupled to DNA double strands, and based on an oxidation reduction potential thereof. Moreover, as a method which needs no modification or the like, a method making use of a surface plasmon resonance phenomenon has been available. Regarding a technology for fixing DNA to an electrode, a method using a thiol-modified DNA probe or the like has been available, which utilizes an action in which a monomolecular film of a free thiol group at the tail end of the DNA forms itself on a full surface.
Among the methods made available in the conventional DNA detection technology, it was necessary to modify the DNA in case of using the RI or fluorescence technology.
The present invention provides a biopolymer (DNA) detector capable of performing direct detection by using the property of DNA without needing any modification of the DNA.
A biopolymer detector according to an aspect of the invention comprises: voltage supplying means for applying a voltage between two electrodes of a casing for housing biopolymers between the electrodes; and measuring means for measuring an electrical characteristic between the electrodes, alternatively a change in the electrical characteristic.
A biopolymer detector according to another aspect of the invention comprises: voltage supplying means for applying a voltage between two electrodes of a casing for housing biopolymers between the electrodes; electrode driving means for changing a distance between the electrodes; and measuring means for measuring an electrical characteristic between the electrodes, alternatively a change in the electrical characteristic.
The voltage supplying means can selectively supply AC or DC voltages, and can draw biopolymers to one or both of the electrodes.
The measuring means can further includes arithmetic processing means for calculating one selected from presence/absence of biopolymers between the electrodes, a present amount, a base length, a concentration, a rate of hybridization, and an amount of hybridization based on a measuring result of the electrical characteristic, alternatively a change in the electrical characteristic. Thus, various characteristic amounts of biopolymers can be measured.
Heating means can be further provided for applying heat to the electrodes to dissociate hybridized biopolymers between the electrodes into a single strand. Thus, the presence of complementary strand biopolymers and non-complementary strand biopolymers can be respectively detected.
According to the detector of the invention, it is only necessary to inject sample DNA between the opposing electrodes. According to this technology, since the amount of present DNA can be physically measured, a concentration or the like can also be measured. Moreover, in the detector, by applying the external force of an electric field to the opposing electrodes, single-strand probe DNA fixed to the electrode surface, and sample DNA that has not been hybridized are drawn to the electrode, to which the probe DNA is not fixed. Accordingly, gene detection can be carried out without needing any washing.
Furthermore, both reacted and unreacted samples are measured by employing the method of the invention. Thus, a clearer result can be obtained.